Isolation and alga-inhibiting characterization of Vibrio sp. BS02 against Alexandrium tamarense

The bacterium BS02 which is closely related to the genus Vibrio sp. and capable of inhibiting the toxic dinoflagellate Alexandrium tamarense was isolated from a mangrove area in Zhangjiangkou, Fujian Province, China. The bacterium was not species-specific since it displayed varying degrees of lysing activities against eight of the eighteen algae tested. There was a close interaction between initial bacterial and A. tamarense cell densities, indicating that algal growth was prompted at low bacterial concentrations, while the number of the alga cells was reduced at high concentrations. Alga-lysing characterization of Vibrio sp. BS02 suggested that the alga-lysing substance was extracellularly produced, less than 500 in molecular weight, as well as non proteinaceous, stable under wide range of temperature and pH conditions, UV radiation, repeated freezing and thawing and heavy metal treatments. These findings suggested that BS02 could play an important role in controlling harmful algal blooms.